prEN IEC 80000-17:2026

• Status: Not Published
• Publication Date: 21-Dec-2027
• ICS: 01.060 - Quantities and units
• Technical Committee: CLC/SR 25 - Quantities and units, and their letter symbols
• Current Stage: 4060 - Enquiry results established and sent to TC, SR, BTTF - Enquiry
• Start Date: 09-Oct-2026
• Completion Date: 09-Oct-2026
• Ref Project: oSIST prEN IEC 80000-17:2026 - Quantities and units - Part 17: Time dependency

• Referred By: prEN IEC 60335-2-11:2025 - Household and similar electrical appliances - Safety - Part 2-11: Particular requirements for tumble dryers
• Effective Date: 10-Feb-2026

prEN IEC 80000-17:2026 is a draft IEC standard in the IEC 80000 series on quantities and units. It specifies how to write and print symbols for time-dependent quantities, including periodic, transient, and random forms, for use in technical documentation and electrical engineering. The document is aimed at anyone who needs consistent, language-independent notation for quantities that change with time.

What does prEN IEC 80000-17:2026 specify?

prEN IEC 80000-17:2026 specifies principles for writing and printing symbols for quantities that depend on time. It focuses on abstract or placeholder quantities rather than specific physical cases, so the symbol rules can be applied broadly in standards, textbooks, reports, and circuit-related documents.

The document is organized into a foreword, an introduction, five clauses, one informative annex, and a bibliography. Clause 1 gives the scope, Clause 2 lists normative references, Clause 3 covers terms and definitions, Clause 4 explains the symbol system, and Clause 5 gives standardized tables for time-dependent quantities.

Annex A is informative and shows examples of alternating, transient, and random quantities. That matters in practice because it shows how the symbol rules are used in real expressions without turning the annex into a separate requirement set.

What are the key requirements of prEN IEC 80000-17:2026?

The main requirement is that symbols for time-dependent quantities should be written in a standardized, language-independent way. Clause 4 says the document uses two symbol-building approaches: additional marks or letter subscripts, and it also allows a combination of both. In practice, this helps authors keep notation consistent across documents and languages.

How does the standard treat instantaneous and average values?

Clause 4.1 says the symbol for a time-dependent quantity implies an instantaneous value. When upper-case and lower-case letters are both used, the lower-case letter represents an instantaneous value and the upper-case letter represents an average value. If the writer wants to state explicitly that the instantaneous value is meant, the letter t may be added in parentheses.

Clause 4.2.3 explains root-mean-square (RMS) value and says the RMS value is the positive square root of the mean of the square over a chosen time interval. For periodic quantities, the averaging interval is usually one period or a multiple of periods. In practice, this tells the reader how to label and interpret measured values such as current and voltage.

The same clause notes that in electrotechnology the RMS values of current and voltage are usually denoted I and U. That matters because it distinguishes the measured effective value from the instantaneous waveform.

How are periodic and sinusoidal quantities handled?

Clause 4.2 says periodically varying quantities may be represented as a superposition of sinusoidal functions, identified as Fourier series. For sinusoidal quantities and their complex representations, the standard uses upper-case and lower-case letters in standardized ways.

This section also links symbol choice to phasor representation and to the terms used for phase and initial phase. In practice, this helps engineers write waveforms, complex quantities, and their real forms without mixing notations.

How are components and subscripts arranged?

Clause 4.3 sets the order of information in subscripts. The first part identifies the type of component, the second part identifies the special component, and the third part identifies the associated value. If a series representation would create long subscripts, a left-hand superscript may be used to show the order of the component.

That is useful when writing harmonic series or multi-component signals, because the notation stays readable while still showing which term is which.

What do the tables standardize?

Clause 5 gathers the standard forms into tables for time-dependent quantities, average quantities, components of a combined quantity, selected instantaneous or average values of a component, and distributions or singularity functions. This is the practical core of the document: it gives the accepted symbol forms for common situations instead of leaving each author to improvise notation.

Annex A then shows how those tables are used in examples. It covers sums and products of constant, alternating, slowly changing, and random components, so readers can see how the notation works for typical waveform combinations.

What terms does prEN IEC 80000-17:2026 define?

The document does not list formal terms and definitions, but it uses several key terms in a specific technical way.

• RMS value - The root-mean-square value is the square root of the mean of the squared quantity over a time interval.
• Phasor - A phasor is the complex-valued representation used for a sinusoidal quantity.
• Alternating component - An alternating component is a time-varying part of a combined quantity, often written with dedicated subscripts.
• Slowly changing component - A slowly changing component is a time-dependent part that varies more slowly than the alternating component.
• Running average - A running average is an average written as a function of time over a moving interval.
• Unit step function - A unit step function is one of the singularity functions listed in Table 5.
• Dirac function - The Dirac function is listed in Table 5 as a singularity function used in time-dependency notation.

Who uses prEN IEC 80000-17:2026?

prEN IEC 80000-17:2026 is used by standards writers, electrical and electronics engineers, technical authors, educators, and metrology professionals who need consistent symbols for time-dependent quantities. It is especially relevant where current, voltage, flux, harmonic content, transients, or random components are described in a formal document.

The foreword shows that the document is of interest to a wide range of IEC technical committees, which reflects its horizontal role. In practice, that means the notation can be applied across many technical fields wherever time-dependent quantities appear in design documentation, calculations, and publications.

What changed in prEN IEC 80000-17:2026 from the previous edition?

prEN IEC 80000-17:2026 is described as an excerpt from IEC 60027-1 and, together with the future Part 16, it will cancel and replace IEC 60027-1:1992+COR1:1993+AMD1:1997+AMD2:2005 ED6.0, Letter symbols to be used in electrical technology - Part 1: General.

The draft also states that it contains Clause 2, tables 9 and 10, and Annex C of IEC 60027-1 Ed 6:1995. That tells the reader the new part reorganizes and republishes selected content from the earlier document.

Which standards are used with prEN IEC 80000-17:2026?

The normative references named in Clause 2 are:

• ISO 80000-2:2019 - Provides the mathematics background used for the notation.
• ISO 80000-6:2022 - Provides the electromagnetism quantities that appear in the examples.
• IEC 60050-103 - Supplies the functions terminology used for the meaning of the symbols.

The foreword also places this part within the wider IEC 80000 and ISO 80000 series. It names IEC parts 6, 13, 15, and 16, and ISO parts 1 to 12, including ISO 80000-3, which helps users see where this part sits among the other quantities-and-units documents.

What does the prEN IEC 80000-17:2026 document contain?

The document contains standardized symbol tables for time-dependent quantities in Clause 5, including forms for instantaneous values, maximum and minimum values, RMS values, average values, combined quantities, and selected singularity functions. It also includes equations for periodic RMS values, running averages, and symbol ordering in subscripts.

Annex A provides worked examples with figures for alternating, transient, and random quantities. Those examples show sums and products of components, which is useful when preparing equations, drafting technical standards, or checking notation in reports and specifications.

SLOVENSKI STANDARD
01-september-2026
Veličine in enote - 17. del: Časovna odvisnost
Quantities and units - Part 17: Time dependency
Grandeurs et unités - Partie 17: Dépendance temporelle
Ta slovenski standard je istoveten z: prEN IEC 80000-17:2026
ICS:
01.060 Veličine in enote Quantities and units
17.080 Merjenje časa, hitrosti, Measurement of time,
pospeška, kotne hitrosti velocity, acceleration,
angular velocity
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

25/853/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 80000-17 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-07-17 2026-10-09
SUPERSEDES DOCUMENTS:
25/844/RR
IEC TC 25 : QUANTITIES AND UNITS
SECRETARIAT: SECRETARY:
Italy Ms Daniela Zambelli
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
TC 1,TC 2,TC 3,SC 3C,SC 3D,TC 4,TC 5,TC 7,TC 8,SC
8A,SC 8B,SC 8C,TC 9,TC 10,TC 11,TC 13,TC 14,TC
15,TC 17,SC 17A,SC 17C,TC 18,SC 18A,TC 20,TC 21,SC
21A,TC 22,SC 22E,SC 22F,SC 22G,SC 22H,TC 23,SC
23A,SC 23B,SC 23E,SC 23G,SC 23H,SC 23J,SC 23K,TC
26,TC 27,TC 29,TC 31,SC 31G,SC 31J,SC 31M,TC 32,SC
32A,SC 32B,SC 32C,TC 33,TC 34,SC 34A,SC 34B,SC
34C,SC 34D,TC 35,TC 36,SC 36A,TC 37,SC 37A,SC
37B,TC 38,TC 40,TC 42,TC 44,TC 45,SC 45A,SC 45B,TC
46,SC 46A,SC 46C,SC 46F,TC 47,SC 47A,SC 47D,SC
47E,SC 47F,TC 48,SC 48B,SC 48D,TC 49,TC 51,TC
55,TC 56,TC 57,TC 59,SC 59A,SC 59C,SC 59D,SC
59F,SC 59K,SC 59L,SC 59M,SC 59N,TC 61,SC 61B,SC
61C,SC 61D,SC 61H,SC 61J,TC 62,SC 62A,SC 62B,SC
62C,SC 62D,TC 64,TC 65,SC 65A,SC 65B,SC 65C,SC
65E,TC 66,TC 68,TC 69,TC 70,TC 72,TC 73,TC 76,TC
77,SC 77A,SC 77B,SC 77C,TC 78,TC 79,TC 80,TC 81,TC
82,TC 85,TC 86,SC 86A,SC 86B,SC 86C,TC 87,TC 88,TC
89,TC 90,TC 91,TC 94,TC 95,TC 96,TC 97,TC 99,TC
100,TA 1,TA 2,TA 5,TA 6,TA 15,TA 17,TA 18,TA 19,TA
20,TA 21,TC 101,TC 103,TC 104,TC 105,TC 106,TC
107,TC 108,TC 109,TC 110,TC 111,TC 112,TC 113,TC
114,TC 115,TC 116,TC 117,PC 118,TC 119,TC 120,TC
121,SC 121A,SC 121B,TC 122,TC 123,TC 124,TC
125,PC 126,PC
127,CISPR,CIS/A,CIS/B,CIS/D,CIS/F,CIS/H,CIS/I
ASPECTS CONCERNED:
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TITLE:
Quantities and units - Part 17: Time dependency

PROPOSED STABILITY DATE: 2030
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IEC CDV 80000-17 © IEC 2026
CONTENTS
Contact . 3
CONTENTS . 1
FOREWORD . 2
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and Definitions . 6
4 Names and symbols for time-dependent quantities . 6
4.1 General . 6
4.2 Quantities that vary with time periodically . 7
4.2.1 General . 7
4.2.2 Sinusoidal quantities. 7
4.2.3 Root-mean-square value ,RMS value, effective value . 7
4.3 Succession and position of information subscripts . 7
5 Tables for time-dependent quantities . 8
Annex A (informative) Examples of time-dependent quantities . 12
A.1 Examples of alternating quantities . 12
A.2 Examples of transient quantities . 17
A.3 Example of a random quantity . 19
Bibliography . 20

Figure A.1 – Sum of a constant component 𝑋0 and an alternating component 𝑥a . 12
Figure A.2 – Sum of two alternating components . 13
Figure A.3 – Product of two alternating components . 14
Figure A.4 – Sum of a constant component and two alternating components . 15
Figure A.5 – Sum of a constant component and three alternating components . 16
Figure A.6 – Product of a varying component and an alternating component . 17
Figure A.7 – Sum of two varying components and one alternating component. 18
Figure A.8 – Sum of a constant component and a random variable . 19

Table 1 – Symbols for time-dependent quantities . 8
Table 2 – Symbols for average quantities . 9
Table 3 – Symbols for components of a combined quantity . 9
Table 4 – Symbols for some instantaneous or average values of a component . 10
Table 5 – Distributions, singularity functions . 10

IEC CDV 80000-17 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Quantities and units -
Part 17: Time dependency
FOREWORD
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IEC CDV 80000-17 © IEC 2026
information, which may be obtained from the patent database available at https://patents.iec.ch.
IEC shall not be held responsible for identifying any or all such patent rights.
IEC 80000-17:202X has been prepared by TC 25/JWG 2: Revision and amendments of IEC-
related parts of ISO/IEC 80000 series of IEC technical committee TC25: Quantities and units.
It is an International Standard.
This 1st edition together with the future forthcoming Part 16 (Printing and writing rules) will
cancel and replace IEC 60027-1:1992+COR1:1993+AMD1:1997+AMD2:2005 ED6.0, Letter
symbols to be used in electrical technology - Part 1: General.
This new part is an excerpt from IEC 60027-1 according to IEC/TC 25 decision 2017/25-07
(Document 25/614/DL). This draft contains Clause 2, tables 9 and 10, and Annex C of
publication IEC 60027-1 Ed 6: 1995.
IEC 80000 consists of the following parts, under the general title Quantities and units:
Part 6: Electromagnetism
Part 13: Information science and technology
Part 15: Logarithmic and related quantities, and their units
Part 16: Printing and writing rules
Part 17: Time dependency
The following parts are published by ISO:
Part 1: General
Part 2: Mathematics
Part 3: Space and time
Part 4: Mechanics
Part 5: Thermodynamics
Part 7: Light
Part 8: Acoustics
Part 9: Physical chemistry and molecular physics
Part 10: Atomic and nuclear physics
Part 11: Characteristic numbers
Part 12: Condensed matter physics
The text of this International Standard is based on the following documents:
IEC CDV 80000-17 © IEC 2026
Draft Report on voting
25/XX/FDIS 25/XX/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English .
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
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– withdrawn, or
– revised.
IEC CDV 80000-17 © IEC 2026
INTRODUCTION
Time-dependent quantities can be periodic, transient or random and can be often represented
by a combination, e.g. sum, product, polynomial, etc., of components which are functions such
as trigonometric functions, exponentials, distributions, etc. They are denoted by specific
symbols which also can express specific characteristics like maximum, minimum, average by
various graphemes like subscripts, superscripts, diacritics, underscore, etc.
For time-dependent quantities, several different systems have been developed and used
depending on the number and the choice of base quantities on which the system is based.
However, in time dependency and electrical engineering, only the International Sys tem of
Quantities, ISQ, and the associated International System of Units, SI, are acknowledged and
are reflected in the standards of ISO and IEC. The SI has seven base units, among them meter,
symbol m, kilogram, symbol kg, second, symbol s, and ampere, symbol A.
The various possibilities for symbols for time-dependent quantities are presented in tables with
examples. No specific quantities are considered but place holders or abstract quantities.
All symbols and graphemes are language independent.
The items given in IEC 80000-17 are generally in conformity with the International
Electrotechnical Vocabulary (IEV).
...